1. Field of the Invention
The invention relates to a touch panel, especially to a capacitive touch panel assembled with a display panel.
2. Description of the Related Art
Most electronic devices, such as PDA, palm-sized PC and information appliance, have a touch display panels. The touch display panel includes a lens, a display panel and a touch panel arranged between the lens and the display panel. In the prior art, the lens and the touch panel are separately formed on different substrates, which are usually glass substrates. The lens and the touch panel are then laminated to form a touch module. The touch module is further stacked up with and attached to the display panel to form the touch display panel. A user can touch objects displayed on the touch display panel with his or her finger or a touch pen to input information or perform an operation.
Please refer to FIG. 6. FIG. 6 is a sectional view of a conventional touch display panel. As illustrated in FIG. 6, in the prior art, a touch panel 6 is disposed between a display panel 2b and a lens 5. A black layer 51 is provided on the periphery of a lower surface of the lens 5. The black layer 51 is stuck to the periphery of the upper surface of the touch panel 6. There is a stick layer 4c disposed between the black layer 51 and the touch panel 6, as shown in FIG. 6. For the conventional touch panel 6, conductive layers are formed on the upper surface of a glass substrate 61. The conductive layers include at least a lower transparent conductive layer 62 and an upper transparent conductive layer 65. The conductive layers may include but not be limited to an indium-tin-oxide (ITO) material. A transparent insulation layer 64 is formed between the upper transparent conductive layer 65 and the lower transparent conductive layer 62. On each periphery of the upper transparent conductive layer 65 and the periphery of the lower transparent conductive layer 62, a metal trace 63 is formed respectively for transmitting signals thereon. The black layer 51 is arranged to cover the metal traces 63 so that the metal traces 63 are not exposed when viewed from above the lens 5 for prettifying the appearance of the lens 5. A transparent overcoat 66 made of insulation material (such as silicon nitride, silicon dioxide, etc.) is formed above the upper transparent conductive layer 65 to prevent the upper transparent conductive layer 65 from being scraped and damaged. The coordinates of a position that has been touched on the touch panel 6 is obtained according to detection of an induced current corresponding to a capacitive generated between the transparent conductive layers 62 and 65 and the human body.
The display panel 2b may include a liquid crystal display (LCD) formed by providing a liquid crystal layer 24b between an upper glass substrate 22b and a lower glass substrate 26b. An upper polarizing plate 21b is provided on a top surface of the upper glass substrate 22b, and a transparent conductive layer 23b is provided between the liquid crystal layer 24b and a bottom surface of the upper glass substrate 22b. A lower polarizing plate 27b is provided on a bottom surface of the lower glass substrate 26b. Another transparent conductive layer 25b is provided between the liquid crystal layer 24b and a bottom surface of the lower glass substrate 26b. The upper glass substrate 22b and the transparent conductive layer 23b form an upper glass electrode substrate. The lower glass substrate 26b and the transparent conductive layer 25b form a lower glass electrode substrate. The display panel 2b and the touch panel 6 are laminated together with a stick layer 4b disposed between them.
As illustrated in FIG. 6, the liquid crystal layer 24b is sandwiched between the upper glass electrode substrate and the lower glass electrode substrate. Driven by an electric field between the upper glass electrode substrate and the lower glass electrode substrate, the liquid crystal molecules contained by the liquid crystal layer 24b are twisted to determine whether light from a light source can pass through. Further, the liquid crystal display displays a colorful image using a color filter for the upper glass substrate 22b. A user then may see an image from the top of the lens 5. The user then is able to perform an operation or input information by touching the lens 5 with the indication conveyed by the image.
As described above, in the prior art, each of the lens 5 and the touch panel 6 is formed on a glass substrate separately and individually, wherein the glass substrate 61 of the touch panel is individually shown in FIG. 6. After separate and individual fabrication, the lens 5 and the touch panel 6 are then laminated. Each of the lens 5 and the glass substrate 61 of the touch panel 6 is made of same glass material, which increases the consumption of glass material in production of the touch display panel. Besides, the assembling process is very complex and time wasting, and it is easy to generate defective products during the lamination process. Furthermore, the thickness of the touch display panel is hard to reduce for both the lens and the touch panel adopt the glass substrates.
In view of the foregoing, there is a need for a capacitive touch panel that can alleviate the aforementioned disadvantages.